Google made its name in search through a simple principle: if lots of other sites point to a particular site that matches a search term, that's probably the most highly thought-of site for that topic. It's rather like asking everyone who's the most knowledgeable about something: they might not all agree, but you'll find a consensus. Before Google, search relied more on who could shout the loudest about themselves – which brought increasingly useless results, just as it would with people.

But the internet being what it is, a place where pretty much anyone can put anything up, sometimes the site that everyone's pointing at isn't tasteful, or polite, or even legal in some parts of the world. That's the risk one takes with free speech: it includes the freedom to offend. But equally, other people can find that "offensive" content amusing or educational or a bolster to their beliefs: is a satirical page about Sarah Palin offensive to women, Republicans, or just the terminally humourless?

Knowing that's how Google's algorithm works, people have cooked up "Googlebombs" to attach particular meanings to people: from 2005 to 2007 a search with the words "miserable failure" directed you to the White House home page, where George Bush was in power. Google subsequently "defused" those bombs by tweaking its algorithm to make such attempts fail.

At the time, Matt Cutts, Google's anti-spam chief, noted that "people assumed that [the results] are Google's opinion, or that Google has hand-coded the results of these Googlebombed queries. That's not true."

And now an ugly image of Michelle Obama has hit the topic of the image search, in part because so many people were linking to it – either in horror or delight – which created a sort of short-lived Googlebomb, and prompted an explanation (not, please note, an apology) from Google, repeating Cutts from 2007: "Sometimes Google search results from the Internet can include disturbing content, even from innocuous queries. We assure you that the views expressed by such sites are not in any way endorsed by Google."

But why not just remove the page from its index? Because Google doesn't want to be seen to be making choices; that would put it into the middle of every battle fought by every special interest group everywhere. Hence: "We do not remove a page from our search results simply because its content is unpopular or because we receive complaints concerning it." The company has already tackled the issue once before, over the search results for the word "Jew", which found all sorts of racist sites.

Only legal action – by the authorities (because the US first amendment allows Google to republish "legal" speech, making it proof against civil action) – can get a page taken out of the index.

But for the rest, all Google can offer is: "We apologise if you've had an upsetting experience using Google. We hope you understand our position regarding offensive results." In other words, don't blame us – blame the world out there.